Pilot valve controlled tracer valve



3 Sheets-Sheet l E. G. ROEHM PILOT VALVE CONTROLLED TRACER VALVE 2 INVENTOR.

[RWlJVG.)?0H/V W, k. mi 91/ ATTORIVZ'YS NOV. 18, 1952 E G, ROEHM 2,618,244

PILOT VALVE CONTROLLED TRACER VALVE Filed March 12, 1947 3 Sheets-Sheet 2 IN VEN TOR. [x wnv 6. Roz-HM BY 51/. 711 091/14 hi 7/.

1952 E. G. ROEHM 2,618,244

PILOT VALVE CONTROLLED TRACER VALVE Filed March 12. 1947 3 Sheets-Sheet 3 INVEN TOR.

[1? WIN 6. XfiIH/V Y ALZQIENZ'Y-S' Patented Nov. 18, 1952 PILOT VALVE CONTROLLED TRACER'VALVE Erwin G. Roehm, Norwood, Ohio, .assignor tov The. Cincinnati. Milling, Machine 00., Cincinnati, Qhin, a corporationof Ohio Application March 12, 1947,. Serial No. 734,096.

1 Claim. (Cl. 121-465) This inventionrelates to automatic pattern controlled mechanisms and moreparticularly to improvements intracer mechanisms therefor.

One of the objects of this-invention is to. reduce or lighten the contact pressure ona pattern bya tracer finger by makingthe deter minationof the amount of this pressure male-- pendent of the weight of the parts connected to the tracer fingerso that this pressure may be made less than the weight of the operating parts connected tothe tracer finger.

Another object of this invention is to improve thatany modificationsmay be made. in the exact.

structural details there shown and described, within the. scope of the appended claim, without departing from or exceeding the. spirit. ofthe invention.

Referring. to the drawings in which. like reference numeralsv indicate like or similar parts;

Figure 1.is ayiew in elevation showing the general. .assembly and mounting of the tracer mechanism embodying the principles. .ofthis invention.

Figure 2 is an enlarged sectional view on. the lineal-2 in Figural.

Figure. .3. is a diagrammatic view of the hydraulic control circuit.

Referring tov the. drawin s and more particularly to Figural, the reference numeral l;5,;1indicates. the main body or housingof the. tracer mechanism which may be suitablyclamped in asplit carrier member II by a clampin screw, indicated-generally by the reference numeral [2. The carrier member ll may be, mounted, for longitudinal adjustment along the faces .13- and IA of a bracket [5, and guided relative thereto bya guide portion I6, Figure 2, formed integral with the carrier II, which is mounted between the guiding face I! of the bracket on oneside and a gib member l8 on the other side. A clamping screw. indicated generally by the reference numeral [.9 is threaded into the guide portion l6 for tightening the bracket against the guide faces l3 and M. Byloosening-the screw [Bean adjusting screw 20, which is fixed against axial movement in the bracket i5 and threaded into.

the guide portion is of the bracket, may: be

rotated to effect longitudinal adjustmentof the carrier l I.

The bracket I5 may be provided with. suitable guide surfaces 22 whereby the parts may: be seecured to a suitable tool carrying slideof apatterncontrolled machine tool, the movement. of which slide is to be controlled by. the .tracer.

The housing It may be vertically adjusted. relative to its carrier Me, which is often necessary; to properly position the tracer relative-1 to..its. pattern without disturbing the. position of. the. cooperating cutter or tool with respect. to. a. work piece. This adjustment is. accomplished means of an adjusting screw- 23 which ismounted in a bracket 24, formed: integral with the housing. It, against axial movement and. is threaded. at. 25 in the carrier H. The adjusting screw 2.3;.is. provided with a suitable. control knob .25. carries. suitablev graduation. marks. 2.6. for-.c Qoperating with. a. fixed reference. mark. 21' formed an; the bracket. 2.4. Thesegraduations. maybe. the nature .of a micrometer mechanism for ac.- curately positioning. the tracer;

Referring to Figure 2. of the. drawin s... Wil be seenthat the. housing: In. 15:131. the form; er a hollow tubular member having a: flanged, tubular member 28 inserted in the; end. thereofandsecured thereto by suitable. means; such as. belts; 2. The upper end of the member 28 is. provided, with a. finished bore 30 and the remaining portion is provided with an internal thread 31. A tracer sleeve carrie 32. is mo nted fer sli ing; movement. the here 30 and is pro d d with a semi-spherical seat 33.. The tracer sleeve 3.4 is provided w t a enla d spherical; per ien 35, the lower part of which rests on-the seat;..'3'3 and the upper part of which isengagedbil' a clamping member 36 whichv is threaded at31. inthe carrier 32. The member 36 is; adjusted rel-as tive to the part 32 to prevent, any. lifting--move-. ment of the sleeve 3. 3 relative to.- its seat. 3,3,but. at the same time to permit universaloscillation of the sleeve 34 aboutthe center of its spherical portion 35.

The member 32 is held for: slid n movement within the bore 3.0 by means of a spring 38, which is mounted W hin. a sprin ret ining-cup. 319. which s a justa l e th thr ads 3 ctr-the.- member 28. When t e member-3.9- is prop rly adjusted... it is locked by a. s t; screw 4.9.. w ich 3 is threaded radially into the member 28. Attention is invited to the fact that the spring 38 is very accurately made and it constitutes the sole supporting means for the tracer sleeve and the parts connected thereto as will be brought out as the description proceeds.

A suitably formed tracer finger 4| is secured in the end of the tracer sleeve as by a set screw 42. The end of this tracer finger is adapted to engage a suitable pattern indicated by the reference numeral 43' as shown in Figure 3.

The tracer sleeve has a long tubular extension 43 formed on the upper side of the spherical portion 35 relative to the tracer finger supporting portion, and is of somewhat the same length as that portion for balancing and operating purposes. In the end of the tubular portion 43 is a plug 44 which has a conical seat 45 formed in the end thereof for receiving a ball 45.

This ball is interposed between the member 44 and a member 41 which is confined for axial sliding movement by anti-friction members in the form of balls 48 which are mounted in a sleeve or retainer 49. The member 41 has a concave depression 58 formed in the end thereof for receiving the ball 46 and the arrangement is such that lateral movement of the member .43 will be transformed by the ball 46 into axial movement of the member 41.

The retainer sleeve 49 is mounted in a socket formed in the end of a flanged member 52 which is secured by bolts 53 to the end of a valve sleeve 54. This valve sleeve is mounted in a bore 55 formed in the housing l8 and is provided with aflange 56 on the upper end through which bolts 51 are passed to secure the sleeve to the housing.

Mounted within the sleeve 54 is a slidable valve member 58, as shown in Figure 3, and this valve member has a bore 59 in which is slidably mounted a pilot valve member 68. A spacer rod BI is interposed between the end of the valve member 60 and the slidable member 41 whereby oscillation of the tracer sleeve 43 will impart axial movement to the pilot valve member 58. The main control valve member 58 has a counterbore 62 in the upper end, which is threaded to receive an adjustable plug 63, which has a light spring 64 interposed between it and the end of the pilot valve plunger 68 for exerting sufficient force to overcome the friction between the member 68 and its bore.

Assuming for the moment that the spring 64 is not under any compression it will now be seen that the lower spring 38 supports all of these moving parts; 32 and 35 which form a retainer for oscillation of the tracer sleeve, the tracer sleeve 34 and tracer finger 4|, the ball 46, the slidable member 41, the spacer BI and the valve member 60. The weight of all these parts will effect a definite amount of compression or shortening of the spring 38.

Since the valve member 58 determines the operation of the parts, it is necessary that this valve have some definite position as a starting point for determining the relative position of the cooperating parts. Therefore, the tracer arm 43 is provided with a flanged member 65, Figure 2, which is secured thereto as by a pin 68, and the spring 38 is so adjusted by rotation of the member 39 that the flange will just come to rest on top. of the member 28. The spring 38 is still supporting the weight of all of these parts. The spring 64 located on top of the valve member 68 is now compressed to provide a few ounces of preload upon the member 68 which is sufficient to overcome any sliding friction between the member 68 and the bore in which it slides. This pre load will not increase the compression of the spring 38 but will be opposed through the flange member 65 resting on the member 28. It should now be apparent that any pressure or force exerted on the end of the tracer finger 4|, such as would be exerted by a pattern must only be sufficient to overcome the resistance of the spring 64 because the full weight of the parts is assumed by the spring 38. It is, of course, recognized that any elongation of the spring 38, which would be caused in this case by upward movement of the tracer, would decrease the upward lifting value of the spring 38 and if this movement were continued until the spring elongated to its free length that its upward lifting value would reduce to zero. However, the upward movement of the tracer valve for complete reversing control is so small that the elongation of the spring is very minute and therefore the decrease in lifting value of the spring is also very small so that for all practical purposes it might be said to be almost the same. However, whatever theoretical diiference there is represents the additional force that must be exerted on the tracer in addition to the small force that must be exerted to overcome the resistance of spring 64. It should thus be evident that by this arrangement of the parts that the actuating force on the tracer to cause actuation of the valve mechanism may be reduced to a matter of a few ounces which is many times less than the weight of the parts supported by the spring 38.

The main control valve plunger 58 which is slidably mounted in the sleeve 54 has its position determined by the pilot valve member 50 in the following manner. A source of hydraulic pressure in the form of a pump 5'? is provided which has an intake 88 for withdrawing fluid from a reservoir 59 and delivering it under pressure to a line 18. The channel HI has a branch connection to a relief valve 7 l to prevent excessive pressure in the line 18. The channel 18 is connected to a space 12 between the end of the plunger 58 and a sleeve 73 which is inserted in the end of the valve sleeve 54.

It will be noted that the valve plunger 58 has a reduced diameter 74 which is sufiiciently long to extend substantially the full length of the sleeve member '13. The pump pressure existing in the space 12 exerts a continuous urge on the valve member 58 in a downward direction as viewed in Figure 3. The space 12 is connected by a channel 14 to a port 15 formed in the sleeve.

54, and this port is in constant communication regardless of movement of the valve 58 with a,

wide annular groove 76 formed in the periphery of the valve 58. Radial ports ll are formed in the groove 16 and the valve member 6|] is provided with a spool 18 to control the flow of fluid through the port 77 and in so doing forms a hydraulic resistance at that port which causes a drop in ressure in the fluid flowing through this port into the annular groove '19 which separates the spool 78 from a second spool 88. The fluid pres sure in the annular groove 19 escapes to reservoir through a port 8| and the flow through this port is controlled by the spool 80 which constitutes a second hydraulic resistance causing a drop between the pressure of the fluid in the annular groove 19 and the atmospheric pressure existing in the return channel 82. 7

Attention is invited to the fact that the lengthof the annular groove 73 is equivalent to the" distance between the center ofthe port 8| and thecenterof the port "I? whereby when the parts are in the position shown one-half of-the port 1! is closediby the spool T8. and one-half of the port 8| is closed by the spool 80 whereby the resistance to flow of fluid into the space I9 is equal to the resistance to flow of fluid out of that space and in accordance with hydraulic law the pressure'in the space it would be equal to one-half of the incoming pump pressure.

A third port 83 is interposed midway between the port TI and 8| to which a channel 84 is connected for conducting the fluid pressure that exists'in the space'lt to the space 85 located between the lower end of the valve plunger and a plugging member BS insertedin the end of the bore of sleeve M. It will now be obvious that the pressure existing in the space 35 will be-equal to one-half of the pump pressure. This pressure will exert" an upward urge on the member 58.

The plugging member 88 has a reduced diameter 81 which extends for a substantial length into a bore 88 formed in the valve member 58, thus sealing off the chamber $5. Attention is invited to thefact that the parts are so proportioned that the end area 89 of the valve member 58 which is exposed to the pressure in the chamber 85 is twice the area of the end face 9|! of the valve 58 which is exposed to the pressure in chamber I2. It should thus be obvious that the full pump pressure acting on the reduced area 98 which is one-half of the area 89, is equal to the product of one-half of the pump pressure acting on the area 89. Thus, the valve plunger 58 would be held stabilized in a given position as determined by the position of the valve plunger ti), and any deviation from this position due to movement of either one of these valve members relative to the other would change the value of the resistances at the ports I? and BI and thereby cause the hydraulic pressure in chamber 85 to increase or decrease and thereby cause a repositioning of the parts in such a manner that the hydraulic resistances can become substantially equal.

The valve sleeve 54 has a pressure port 9| which is branch connected to the channel In, and the valve 58 is provided with a spool 92 which is of a width equal to the width of the port SI and movable relative thereto to control the flow of fluid pressure therethrough and direct it into either the annular space 93 or the annular space 94 of the valve plunger. The space 93 is in communication with a port 85, and the space 94 is in communication with a port 86, and channels 97 and 98 extend from these respective ports to ports 99 and I of a start and stop selector valve IOI. This valve has a plunger H52 in which are formed annular grooves I63 and I02.

When the valve plunger is in the position shown in Figure 3, the port I00 is connected by the annular groove I03 to port I05, and simultaneously port 99 is connected by annular groove I04 to port "it. Channels I01 and I08 extend from ports I and I as to opposite ends of a cylinder I09 which contains a piston IIU that is connected by a piston rod III to a slide H2. The slide I12 diagrammatically illustrates the slide which would carry the tool and the tracer mechanism such as bracket I5 whereby the tracer may control the position of a tool with respect to a work piece in accordance with its cooperating pattern.

The valve sleeve 54 is provided with a pair of exhaust ports H3 and H4 which are connected 6 by branch channels to a main returnline H5. These ports are so located that up'on -upward movement of thevalve plunger 58, the portis connected to the exhaust port ll3 by thezannular groove 93 while the pressure port 9| is=conneot ed to porttfi, and upon downward movement of the valve plunger the port '96 is connected to the exhaust port H4 by the-annular groove 94 while the pressure port-9| is connected to themo'tor port 95. It will thus be seen that "the valve plunger" 58 is capable of controlling reversible operation of the slide I 2.

In setting up the device it will be obvious that since the position of the pilot valve til inavertica l plane is determined by the spring 38-and the flanged member 65, and that the position'o'f the valve member 53 is determined by the position of the valve till, the sleevefi' l must be'axially adjustable to position the pressure port 9| above the valve spool when the traeera-rm is in undeflected position. This is accomplished byany suitable means such as a set screw 56" threaded in the flange 55.

With respect to the general operation of "the device when the tracer is not in use the stop valve plunger It? is shifted upward from the position shown, in which position it is held by a detent means, indicated generally by the reference numeral lit, and in this position the port N35 is connected by the annular groove I93 to *a pressure port i ll which has a branch connecting line M8 to the pump supply line-Ill. This puts fluid pressure in the lower'end of the cylinder "I89 and holds the slide H2 in its upward position. To facilitate this the port liit is connected :by valve groove I64 to port Ila-which has abranch connection I23 to the return -line H5. At this time the tracer sleeve 34 is undeflected and the central axis HQ, as indicated in Figure 2, is in line with the axis I253 of the pilot valve Bil whereby the valve fill is allowed to move down a predetermined amount as determined by the ball 66 and in this position the valve spool 92 is below the port 9| as viewed in Figure 3 and pressure is connected to the channel 91.

Thus, when the stop valve plunger I02 is shifted to a running position, fluid pressure will enter the upper end of cylinder I89 and the slide I 12 will move downward to cause engagement of the tracer finger ll with the pattern 43. This downward movement will cause deflection of the tracer and upward movement of the pilot valve plunger 6i to a suflicient extent to cause upward movement of the main control valve 58 until it reaches a central position, thereby closing the pressure port QI and holding all the parts in a stabilized or neutral position. Upon relative movement of the pattern relative to the tracer finger M the slide I|2 will be caused to move up or down in accordance with the shape of the pattern and in accordance with the established practice of pattern controlled machines.

In machines where the work is supported on superimposed cross slides such as diagrammatically indicated by the reference numerals |2I and I22 having screw feed shafts I23 and I24 there is a possibility that the operator in rotating the manual controls I25 and I25 may not be watching the tracer particularly and cause collision of the tracer finger with some object and which, if the movement continued, would break ofi the tracer finger. It will be obvious that such collision will cause deflection of the tracer and if this movement is excessive it will cause upward movement of the valve plunger 58 sufiiciently to connect the'pressure groove 16 with a port I21 which has a channel I28 connected thereto and this channel has branch connections to hydraulic interlock plungers I29 and I30. These plungers, when extended, are adapted to engage toothed wheels I30 and l3l attached to the screws I23 and I24, thereby locking the parts against rotation. When the valve returns, the fluid pressure is adapted to leak through the resistance 132 to the return line I 15.

There has thus been provided an improved tracer control mechanism which is so constructed and which may be so adjusted that a very light pressure exists between the tracer finger and the pattern, thereby making the device more sensitive to variations in the shape of the pattern and also decreasing wear between the parts.

. What is claimed is:

- A tracer mechanism comprising a housing having a valve chamber formed therein provided with fluid pressure and exhaust connections, a pair of motor ports and an interlock port, a main valve slidable in said chamber and having means thereon when in a central position to neutralize said motor ports and close said interlock ports, said main valve having a closed passage therein, a pilot valve slidably mounted in said closed passage, said pilot valve having an annular groove formed therein, resistance ports in said main valve at opposite ends of said groove and continuously connected to said pressure and exhaust connections respectively for continuously maintaining fluid flow under an intermediate pressure through said groove, means connecting said pressure connection to one end of said valve chamber containing the smaller end of said valve, means continuously connecting the intermediate pressure in said groove to the other end of said valve chamber, a tracer supported in said housing and operatively connected for moving the pilot valve through an intermediate range of movement to shift said control valve on opposite sides of its central position to alternately connect said motor ports to said pressure and exhaust connections respectively, said interlock port closing means on the control valve being responsive to an extended movement of said control valve caused by the tracer to open said interlock port and connect said pressure connection thereto.

ERWIN G. RO-EHM.

REFERENCES CITED The following references are of record in the 'file of this patent:

UNITED STATES PATENTS Number Name Date 734,285 Thomann July 21, 1903 929,206 Gelpke July 27, 1909 2,101,712 Johansen Dec. 7, 1937 2,106,684 Ring et al -1 Jan. 25, 1938 2,154,718 Bannon Apr. 18, 1939 2,237,038 Moore Apr. 1, 1941 2,332,532 Roehm Oct. 20, 1943 2,395,525 Wilkie Feb. 26, 1946 2,412,549 Yates et al Dec. 10, 1946 2,424,031 Heer July 15, 1947 2,491,551 Cross Dec. 20, 1949 2,511,056 Wetzel June 20, 1950 FOREIGN PATENTS Number Country Date 550,473 Germany May 18, 1982 

